1、Standard Method of Test for Bend Test for Bars for Concrete Reinforcement AASHTO Designation: T 285-89 (2015) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4g T 285-1 AASHTO Standard Method of Test for Bend Test
2、for Bars for Concrete Reinforcement AASHTO Designation: T 285-89 (2015) 1. SCOPE 1.1. This method covers a bend test for evaluating the ductility of bars used for concrete reinforcement. 1.2. The units of measure to be used shall be either SI units or inch-pound units (shown in parentheses in this s
3、tandard) depending on the units used in the applicable material specification. 1.3. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 31M/M 31, Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement M 322M/M 322, Rail-Steel an
4、d Axle-Steel Deformed Bars for Concrete Reinforcement 3. SUMMARY OF TEST METHOD 3.1. The test is made by bending test specimens around pins of appropriate diameters until the specified angle of bend has been achieved. Test specimens are expected to withstand bending without cracking. The speed of be
5、nding is ordinarily not an important factor. The severity of the test is primarily a function of the angle of bend and inside diameter to which the specimen is bent, and of the cross section of the specimen. 4. APPARATUS 4.1. The bend test apparatus shall provide for: 4.1.1. Continuous and uniform a
6、pplication of force throughout the duration of the bending operation (Note 1). 4.1.2. Unrestricted movement of the specimen at points of contact with the apparatus and bending around a pin free to rotate, or bending about a central pin on a simple span with end supports free to rotate. The end suppo
7、rt must be strong enough and sufficiently rigid to resist significant deformation. 4.1.3. Close wrapping of the specimen around the pin during the bending operation. 4.2. The diameter of the pin around which bending occurs shall not differ from the nominal value by more than 2 percent or 3 mm (0.1 i
8、n.), whichever is greater. The pin shall be made of steel, and the surface in contact with the bar shall be uniformly curved around the axis of the pin, free of dents and flat spots. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a
9、violation of applicable law.TS-4g T 285-2 AASHTO 4.2.1. The nominal diameter of pins shall be as specified in M 31M/M 31, M 322M/M 322, or other specification, as appropriate, based on the nominal diameter of the bar. Note 1Application of force by hand usually does not satisfy this requirement of th
10、e method. Note 2Bars of size numbers 45 and 55 (14 and 18) are normally specified for use without bending. Consequently, some laboratories are not equipped to conduct bend tests of such bars. 5. SAMPLING 5.1. Sampling shall be performed in accordance with the requirements of relevant specifications.
11、 5.2. Specimens shall be the full section of the bar as rolled and the length shall be sufficient to permit free bending to the angle specified. 6. CONDITIONING 6.1. The temperature of the room in which tests are performed shall be maintained above 15C (60F) at all times. Specimens that have been ex
12、posed to temperatures of less than 15C (60F) in the preceding 24 h shall be brought to test temperature by storage in the laboratory air for at least 24 h prior to test or by immersion in water maintained at a temperature of 15 to 32C (60 to 90F) for at least 1 h prior to test. 7. PROCEDURE 7.1. Pla
13、ce the specimen in the bend test apparatus in such position that the plane intersecting the longitudinal ribs is parallel to the axis of the pin. 7.2. Apply force to the test specimen continuously and uniformly throughout the bending operation. 7.3. Discontinue the application of force when the angl
14、e of bend specified in the material specification has been achieved before rebound. 7.4. Examine the tension surface of the specimen for cracking. 8. REPORT 8.1. The report shall include the following: 8.1.1. Specimen identification; 8.1.2. Steel specification designation, grade, and bar size of the
15、 specimen; 8.1.3. Pin diameter and angle of bend; and 8.1.4. Whether the specimen passed or failed to meet requirements. 9. PRECISION 9.1. A precision statement is not made for this method because the test result is a non-numerical report of success or failure. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
